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tony
Bronze Member
United Kingdom
142 Posts |
 Posted - 08/29/2008 : 20:46:56
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| Relaced C20, R41 and R42. Still exactly the same. Wasn't expecting much, to be honest. The only place left to look is the muting circuit, but we've already tried it with D5 removed.... |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 08/29/2008 : 20:51:49
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quote:
Originally posted by tony
Relaced C20, R41 and R42. Still exactly the same. Wasn't expecting much, to be honest. The only place left to look is the muting circuit, but we've already tried it with D5 removed....
Muting circuit is fine - removing D5 disconnected the NE570 from it and the problem persisted.
What the hell have we missed? Pics would be really helpful...
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tony
Bronze Member
United Kingdom
142 Posts |
Posted - 08/29/2008 : 21:18:08
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Here are some pics, anything in particular you want to see?
In this pic you can see the new NE570, the two new tantalum gain caps, the new 47uf cap - it looks bigger there than it really is. C29 is still out of circuit.
In this pic you can see the underside of the same part of the board - pins 1 - 8 run from bottom to top along the left by the "G" ground symbol and pins 9-16 run down opposite. Pins 14 and 15 are on the little island which they share with R40 (R43). As a visual reference, the two tantalum caps are visible peeking out from the bottom.
Ignore that bit of wiry looking stuff by the number "1", it's a cat hair.
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Edited by - tony on 08/29/2008 21:30:19 |
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tony
Bronze Member
United Kingdom
142 Posts |
Posted - 08/30/2008 : 03:36:02
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So, to summarise.....
The pinouts on the expander produce the same result with:
Every component around the NE570 expander checked or replaced.
The expander isolated from the circuit (via D5 and C29)
The pedal works with:
The expander totally isolated from the circuit/signal path (via R40 (R43) and C29).
It has to be the chip. There is simply nothing else there. I've done nothing to it to kill it. Maybe I'm just phenomenally unlucky with NE570s. |
Edited by - tony on 08/30/2008 12:15:18 |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 08/30/2008 : 04:12:02
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quote:
Originally posted by tony
So, to summarise.....
The pinouts on the expander produce the same result with:
Every component around the NE570 expander checked or replaced.
The expander isolated from the circuit (via D5 and C29)
The pedal works with:
The expander totally isolated from the circuit (via R40 (R43) and C29).
It has to be the chip. There is simply nothing else there. I've done nothing to it to kill it. Maybe I'm just phenomenally unlucky with NE570s.
Much as i disbelieve the probabilities involved, it almost has to be that. Unless there is a hairline crack we just cant see/find. |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 09/03/2008 : 02:41:36
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RIGHT!!
I am serendipitously now the proud owner of a long-chip DD-3 which is identical to your DD-2 (truly - it's just a rebadged DD-2).
I will take some measurements around the compander and take a bit of a poke with the scope and see if I can see anything that is materially different to what you have reported.
Can't say when I'll get to do that exactly - hopefully this week, ceretainly by the weekend.
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 09/03/2008 : 09:20:55
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quote:
Originally posted by Laurie
RIGHT!!
I am serendipitously now the proud owner of a long-chip DD-3 which is identical to your DD-2 (truly - it's just a rebadged DD-2).
I will take some measurements around the compander and take a bit of a poke with the scope and see if I can see anything that is materially different to what you have reported.
Can't say when I'll get to do that exactly - hopefully this week, ceretainly by the weekend.
Hi Laurie
Congrats on the DD-3 (long DIP chip). 
You won't look back, well maybe? If you compare it to your getting more vintage every day  DD-7.
Regards Dr. Bob
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tony
Bronze Member
United Kingdom
142 Posts |
Posted - 09/03/2008 : 18:56:44
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quote:
Originally posted by Laurie
RIGHT!!
I am serendipitously now the proud owner of a long-chip DD-3 which is identical to your DD-2 (truly - it's just a rebadged DD-2).
I will take some measurements around the compander and take a bit of a poke with the scope and see if I can see anything that is materially different to what you have reported.
Can't say when I'll get to do that exactly - hopefully this week, ceretainly by the weekend.
Cool!
Any excuse, eh Laurie? |
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starr36
Platinum Member
Canada
1172 Posts |
Posted - 09/03/2008 : 19:37:32
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quote:
Originally posted by Laurie
quote:
Originally posted by starr36
i am flabberghasted.
when this is done, we can talk about my DD-2 that 'can't tell you've turned the feeback knob down"
no, really, we should be taking a collection for starbucks gift cards for something....
fascinating read.
No problem starr36! But based on our success with tony's DD-2 it might take a while to figure yours out
Where in Canada are you? If you are in Calgary, bring it around and I can have a look at it on the scope...
omg yes I am in Calgary!!!! I can't believe I missed this post. I have the schematics too, plus, due to my job "I have a lot of flexibility"
I am at the bottom of the city, so no matter where I go, its usually always me doing the "going". |
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tony
Bronze Member
United Kingdom
142 Posts |
Posted - 09/04/2008 : 17:05:36
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OK, replaced the compander (again) and reinstalled C29 and the problem persists in exactly the same way. Something about the way that compander is hooked up is killing the expander signal.
Pedal continues to confound..... |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 09/04/2008 : 17:48:52
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I'll get to my DD-3 on the weekend (have some mods to do for friends-of-friends tonight/tomorrow).
Now that we have a known good "control" it will be easy (but maybe time consuming) to track down the problem.
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tony
Bronze Member
United Kingdom
142 Posts |
Posted - 09/10/2008 : 18:47:16
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Hey Laurie, not to nag or unnecessarily revive this thread or anything (I would like it to die, too). Just wondering if you've had a chance to do any probing inside your DD3 yet? Particularly on the strength of the probed signal out of pin 10. Be great to have a working unit to compare to.
I think I may have mentioned this in a PM, but I noticed recently that I still get weak echoes out of pin 10, but the same echoes sound strong and clear (slightly stronger that the dry signal, as they should at maximum effect level) going into and out of the compressor, so after having been through the expandor !!!!
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Edited by - tony on 09/10/2008 18:48:33 |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 09/10/2008 : 19:12:08
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quote:
Originally posted by tony
Hey Laurie, not to nag or unnecessarily revive this thread or anything (I would like it to die, too). Just wondering if you've had a chance to do any probing inside your DD3 yet? Particularly on the strength of the probed signal out of pin 10. Be great to have a working unit to compare to.
I think I may have mentioned this in a PM, but I noticed recently that I still get weak echoes out of pin 10, but the same echoes sound strong and clear (slightly stronger that the dry signal, as they should at maximum effect level) going into and out of the compressor, so after having been through the expandor !!!!
Hi Tony! Crazy at the Laurie household the last week... Had hoped to get to it last weekend, but wont get the time until this coming weekend. Will let you know what I find...... |
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Dirk_Hendrik
Copper Member
Netherlands
28 Posts |
Posted - 09/23/2008 : 10:09:30
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Of all the DD2's and DD3's I've seen the most common problem is leaking 10uF electrolitic capacitors which do result in exactly the problem you're describing. Find tem and replace them. ALL of them or sooner or later your problem will come back.
Also check this thread:
http://www.freestompboxes.org/viewtopic.php?f=10&t=2201 |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 09/23/2008 : 12:30:00
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Hi Dirk_Hendrik
Welcome to our forum, from Australia.
You yourself, have a very informative & nice site.
I believe Laurie or another member here, posted a link to your Ibanez AD9 schematic, on one of our recent threads.
BTW, the link you posted to freestompboxes.org,
requires that you are a registered member to view that particular page.
Regards Dr. Bob
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Topic |
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DD 2 problems
